The present disclosure relates generally to the field of variable air volume (VAV) controllers for heating, ventilation, and air conditioning (HVAC) systems. The present disclosure relates more particularly to systems and methods for conducting damper performance diagnostics in a flow control unit.
Differential pressure (sometimes called dynamic pressure or velocity pressure) is defined as the difference between total pressure (e.g., stagnation pressure) and static pressure in a moving gas or fluid. Differential pressure may be thought of as a kinetic energy of the moving gas or fluid per unit volume. Differential pressure is related to gas or fluid velocity according to the equation Pd=0.5ρv2, where ρ is the density of the gas or fluid and v is the gas or fluid velocity. Differential pressure may be determined by subtracting a measured static pressure from a measured stagnation pressure.
In a HVAC system, a flow control unit such as a variable air volume box or air handling unit may include a damper for regulating the rate of gas or fluid flow. The damper may variably open and close to adjust the flow rate of a controlled gas or fluid (e.g., air) through the flow control unit. Typical methods for assessing damper performance are conducted at a supervisory level within the HVAC system and often rely on data from multiple sensors in conducting the assessment. For example, a sensor measuring the air temperature in a building zone may supply temperature data used in the assessment. It is often difficult to determine whether a damper is operating properly based on such assessments.